Fuze with delay firing and impact firing features



March 5, 1968 G. WEBB 3,371,608

FUZE WITH DELAY FIRING AND IMPACT FIRING FEATURES Filed June 1, 1967 INVENTOR.

GEORGE WEB B BY W ATTORNEY.

United States Patent 3,371,608 Patented Mar. 5, 1968 3,371,608 FUZE WITH DELAY FIRING AND IMPACT FIRING FEATURES George Webb, Richmond, Ind., assignor to Avco Corporation, Richmond, Ind., a corporation of Delaware Filed June 1, 1967, Ser. No. 642,931 Claims. (Cl. 10272) ABSTRACT OF THE DISCLOSURE This fuze is adapted to'be installed in a spinning missile or bomblet. It provides for either delayed firing or impact firing. A weighted slider carries a first ignition train for delayed firing and a second ignition train for impact firing. In response to spin, the slider moves the first ignition train into contact with a first firing pin and sets up conditions for delayed firing. Additionally, it aligns the second ignition train with a second firing pin so that impact firing occurs in response to displacement of or relative to the second firing pin. Adjacent the second firing pin is a ball bearing. Transverse impact forces cause firing by moving the ball against the second firing pin. A spring is interposed between the second firing pin and the housing frame which secures the slider so that the second firing pin andball move to cause firing on impact with the slider end of the fuze. The housing frame moves to cause firing in the event of axial impaut forces with the ball end of the fuze.

Field of the invention The present invention relates to mechanical fuzes in ordnance and it provides a fuze which is of utility with pyrotechnic or explosive components and causes firing either on impact or after a predetermined delay.

The primary object of the invention is to provide a fuze with simple and sensitive initiating means which will cause firing and override the delay feature of the fuze if impact occurs before the expiration of the delay time.

Other objects of the invention are to provide a fuze which is characterized by the following advantages:

(1) Insurance against arming except under conditions of spin;

(2) Firing of primers by inertia forces and not stored energy;

(3) The use of compression springs which are never more than partially compressed;

(4) A small number of moving parts;

(5) An assembly without critical clearances and tolerances;

(6) Adaptability to duplication by mass production methods;

(7) Ready alteration of arming characteristics by modification of springs;

(8) Fail-safe operation if the desired spin rate for arming is not attained;

(9) The achievement of safety by mechanical misalignment.

For a better understanding of the invention together with other and further objects, advantages and capabilities thereof, reference is made to the following description of the appended drawings, in which there is shown a preferred embodiment of fuze in accordance with the invention.

Description of the drawings FIG. 1 is an end view through a fuze structure in accordance with the invention, the rear plate being removed; and FIG. 2 is a view, generally in section, as taken along section line 22 of FIG. 1 and looking in the direction of the arrows.

Detailed description of the invention Referring now to the drawings, attention is first invited to the arming means or slider group 10, 11, which may be made of brass and plastic. The slider group cornprises a brass weight member 10 and a plastic carr1er member 11, suitably mechanically joined as indicated at 12. The carrier is transversely bored to provide a mounting for an igniter 13 and a stab primer 14. These elements are referred to as the second ignition train. It is displaced from point 20 of firing pin 18 when the fuze is in unarmed condition. The carrier and the weight 10 are bored, in a direction lateral to the central axis of the fuze, to provide a mounting for a pyrotechnic delay element 15 and a stab primer 16 (i.e., the first ignition train). Sup port for the operating parts of the fuze is provided by a housing frame 17 which is generally of well-shaped configuration to provide a large bore in which the firing pin 18 is mounted in pistonlike fashion. The housing 17 is centrally apertured at 19 and this aperture is in alignment with the point 20 of the firing pin. An impact spring 21 is disposed between the fuze housing 17 and an annular formation in the rear face of the firing pin member 18. This pin member is of pistonlike formation and there projects from its rear face the firing pin point 20,

Positioned between the concave frontal face of the firing pin and a front end plug 22 is a ball bearing 23. The fuze housing 17 and the other parts are disposed within a cylindrical cover 24, the rear face of which is underlaid by plate 25. Both the rear face of 24 and plate 25 are centrally apertured at 38 to establish communication with the main pyrotechnic material charge (not shown) located rearwardly. The brass slider weight 10 and the plastic carrier member 11 are so formed as to slide within a track located between the top plate 25 and the rear face of the fuze housing. An additional firing pin 26 projects upwardly from the side of the cover 24, at a position which is in axial alignment with the elements 15 and 16. The pin 26 is referred to as the first firing pin and pin 18 as the second firing pin.

Returning now to the track in which the carrier 11 and associated weight 10 slide, that track is formed with a portion 27 of approximately constant width, a portion of enlarged width which provides an arcuate shoulder 28 and a third portion of still greater width which provides an arcuate shoulder 29. A locking pin 30 resides between shoulder 28 and a complementary shoulder 31 formed on weight 10. It will be understood that a similar locking pin 32 is likewise recessed between similar complementary shoulders formed by the weight and the housing.

The carrier 11 and the fuze housing 17 are suitably bored to provide for the engagement, release and sliding movement of arming weights 33 and 34. The weights 33 and 34 are normally biased into latching position by arming weight springs 35 and 36.

Referring to FIGURE 1, the operation of the fuze is now described.

It is assumed that the fuze is used in conjunction with an air-dropped bomblet which rotates about a central axis 37. It is also assumed that the specified spin rate is the minimum spin rate based upon the expected speeds and deployment methods to be used with the weapons system. Lower spin rates would cause non-function or fail-safe operation of the weapon. Finally, the axis 37 of the fuze is common to the spin axis of the bomblet.

The cycle of fuze operation is as follows:

After deployment of the bomblet, when the fuze reaches the specified spin rate, the arming weights 33, 34 move radially outwardly, being forced by the centrifugal force. With the arming weights displaced outwardly, the slider group 10, 11, moves into the armed position, as forced by the centrifugal force, aligning 13, 14, 19 and 20. The

3 kinetic energy produced by the slider and weight 10, 11 in the process of arming the fuze is used to impact 26 and fire the primer 16 and delay element 15. With the slider and weight 10, 11 in the fully armed position, the locking pins 30, 32 are rolled radially outwardly by centrifugal force to lock the slider 10 in the armed pos1t1on, placing the pins in shear between the slider and the fuze housing, i.e., for example between shoulders 31 and 29. The.

delay element 15 burns the required time and in turn fires the igniter 13 which finally fires the flame material (not shown) located to the rear of aperture 38. If impact occurs before the required delay time has elapsed, the firing mechanism 18, 23, 17 will initiate the primer 14 placed next to the igniter 13.

The impact firing mechanism 18, 23 is a simple ball cam mechanism used in conjunction with the housing 17. This mechanism has three modes of operation;

(a) When impact is normal to the fuze axis, the inertia force of the ball 23 overcomes the firing pin spring 21 as the ball cams the firing pin point 20 into the primer 14.

(b) When the impact occurs at the slider or rear end of the fuze, the inertia force of the firing pin 18 and ball 23 is used to overcome the spring 21 and fire the primer 14.

(c) If impact occurs at the ball or front end, the inertia force of the housing 17 and slider assembly 10, 11 will drive the primer 14 into the firing pin point 20.

The net result is a firing mechanism which has three modes of operation.

The discussion of the specific embodiments assumes that the fuze is employed to ignite a pyrotechnic materialv However, the fuze in accordance with the invention can likewise be used with high-explosive materials by using a delay detonator in place of the pyrotechnic delay element 15, a stab detonator in place of the element 16 and a stab detonator in place of the elements 13 and 14.

While there has been shown and described what is at present considered to be the preferred embodiment of the invention, it will be understood by those skilled in the art that various changes and modifications may be made therein without departing from the scope of the invention as defined by the appended claims.

I claim:

1. In a fuze adapted to be installed in a spinning missile, the combination of:

delay firing means comprising a first firing pin and a first ignition train including a delay element,

the first ignition train being normally spaced from said first firing pin,

impact firing means including a second firing pin and a second ignition train normally displaced from the second firing pin,

an arming means formed to carry both of said ignition trains,

said arming means being movable in response to p to impact the first ignition t-rain against the first firing pin to initiate firing after a predetermined time following the movement of the arming means,

said arming means aligning the second lgllltlQlThIEllIl with the second firing pin whereby impact -ll'lltlates firing at a time prior to the expiration of said delay.

2. The combination in accordance with claim 1 wherein the impact firing means comprises a housing member formed to provide mountings on which the arming means and the second firing pin move.

3. The combination in accordance with claim 2 in which the housing member is formed with an axial bore, in which the second firing pin moves, and a face on which the arming means moves, the arming means being a weighted slider and the second firing pin projecting axially through said housing member.

4. The combination in accordance with claim 3 and a compression spring disposed between the second firing pin and the housing.

5. In a fuze adapted to be installed in a spinning missile, the combination of:

a housing member formed to define an axially extending interior bore terminating in a wall having a central aperture;

a piston-like firing pin formed with a projection extending axially into said aperture and with a concave face;

a bearing reposing against said face;

a spring disposed between the housing and the firing pin and yieldable on impact to permit relative motion of the housing and firing of the fuze in response to inertia forces to cause said pin to project through said aperture;

arming means comprising a slider member and a weight secured together to slide transversely;

ignition means carried by the slider member and adapted to be positioned in alignment with said firing pin when the fuze is armed; and

means including another ignition means carried by the slider member and another firing pin disposed in alignment with said other ignition means for producing delayed firing in the absence of impact, the lastmentioned ignition means being disposed longitudinally of the slider and transversely of the axis of the fuze.

References Cited UNITED STATES PATENTS 2,472,821 6/1949 Graumann 10279 2,537,855 1/1951 Porter 10279 3,078,802 2/1963 Sturrock 10272 BENJAMIN Av BORCHELT, Primary Examiner. G. H. GLANZMAN, Assistant Examiner. 

